1. Field of the Invention
The invention relates to fluid regulators and more particularly to a pressure relief valve with improved characteristics.
2. Description of Related Art
A conventional pressure relief valve is shown in FIGS. 1 and 2 and comprises a cap 1 including an inlet 11, a Venturi tube 12 in one end of the inlet 11, a bypass channel 13 adjacent to the Venturi tube 12, an outlet 14 at the other end of the inlet 11, a bonnet 15 for concealing the outlet 14 and including a central threaded hole 152 and a plurality of vents 151 around the threaded hole 152, and a thumb screw 16 threadedly inserted through the threaded hole 152 to either block the outlet 14 (see FIG. 1) or open the outlet 14 (see FIG. 2). In the later condition, pressurized fluid (e.g., air or gas) may flow out of the outlet 14 and release to the atmosphere via the vents 151 due to the disengagement of the thumb screw 16 from the outlet 14.
However, in a lock-up condition (i.e., the outlet 14 being blocked by the thumb screw 16), internal pressure of a pressure vessel fluidly attached to the pressure relief valve may build up to a value greater than a preset pressure. As a result, the pressure vessel may malfunction, break, or even explode.
Thus, the need for improvement still exists.